Area Forecast Discussion
Issued by NWS Burlington, VT

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926 FXUS61 KBTV 172016 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 316 PM EST Fri Nov 17 2017 .SYNOPSIS...
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A brief area of high pressure over the region today will continue to provide dry weather to the North Country through most of Saturday before the next low pressure system brings another round of mainly rain Saturday night into Sunday morning. Rain showers transition to mountain snow showers Sunday afternoon, with dry conditions expected late Sunday night into Monday as high pressure returns.
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&& .NEAR TERM /THROUGH SATURDAY NIGHT/...
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As of 316 PM EST Friday...It`s taken most of the day, but we`re finally seeing sunshine across the majority of the forecast area this afternoon as low pressure continues to exit northeast into the Gulf of St. Lawrence and a brief area of high pressure is building in from the west. Upper ridge is situated over the eastern Great Lakes which will allow some mid and high clouds to work into the region during the overnight hours, but skies should remain fairly clear through midnight before increasing, which allow temps to drop mainly into the teens. Different story across the high peaks which are sitting in the teens this afternoon, but will gradually warm through the night into the low/mid 30s by dawn as mid-level warm advection develops ahead of our next system. Next system begins to approach the region Saturday, but trends amongst the latest guidance continues to be towards a later arrival time of precipitation so feel most of the daylight hours of Saturday will actually be dry. Synoptic setup will be a developing area of low pressure over the Ohio Valley Saturday morning, tracking northeast into the eastern Great Lakes Saturday night to the vicinity of Ottawa by 12z Sunday morning. Increasing southerly flow ahead of the attending warm front will usher in seasonably warm temperatures Saturday afternoon in the 40s area-wide to near 50 for some locations. Precipitation arrives around the 6-8PM timeframe across western New York, and shifts east into Vermont through the overnight hours. By this time, warm air advection will be strong enough that temperatures while cooling slightly through the night, will still support rain as the dominant ptype. Area of some concern will be across the far Northeast Kingdom where some cold air damming looks likely keep temps at or below freezing for a period late Saturday night into early Sunday where some light ice accumulations are possible.
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&& .SHORT TERM /SUNDAY/... As of 400 AM EST Friday...Global 00Z models remain consistent in showing deep ~ 980 mb low pressure tracking into the St. Lawrence Valley Saturday night into Sunday with a variety of weather for the forecast area. This morning`s 00Z NAM deterministic run showing a more pronounced southerly surface low track remains a clear outlier and has been discounted once again. With the anticipated low track temperatures will hold steady in the lower 40s or slowly rise into the mid and upper 30s depending on locale into the overnight hours under increasing southerly flow. The only exception will be the far northern St. Lawrence Valley where pressure-driven channeling effects will likely keep stubborn northeasterly flow locked in much of the night as the low approaches. These trends are in close agreement with the latest GFS and ECMWF MOS-based guidance with a bit of our prior forecast thrown in for good measure. This supports widespread, mainly light to moderate precipitation mainly in the form of rain overspreading the forecast area Saturday evening into Saturday night. Any light snow or sleet would be very early on and at the highest elevations of the northern mountains. By 12Z Sunday the surface low should be situated near Montreal and will exit quickly northeast during the day pushing a very sharp cold front across the area during the morning hours. Impressive 3-hourly pressure rises from 3-9 mb immediately behind the front support persistence in showing winds trending quite gusty from west/northwesterly in the 25 to 40 mph range by late morning into the afternoon hours. Additionally, given the tight baroclinicity along the boundary a band of briefly heavy showers will be possible with this feature. Highs to range in the 37 to 42 range during mid- morning across the Adirondacks/St. Lawrence Valley before falling by late morning into the afternoon, and the lower to mid 40s across VT before falling as well by afternoon. As colder air pushes into the area some minor light snow accumulations will be possible across the Adirondacks and northern Greens to the order of a dusting to an inch or so. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... As of 400 AM EST Friday...Sensible weather conditions then gradually quiet down Sunday night as parent upper trough pulls east and surface high pressure builds in from the upper Midwest and Great Lakes. Any lingering snow showers or flurries will end through the evening hours as skies gradually trend partly cloudy and gusty winds slowly abate overnight. Low temperatures by sunrise Monday seasonably chilly in the teens to lower 20s. After a tranquil though chilly day on Monday the typical up and down temperature roller coaster cycle of November re-asserts itself into the mid-week time frame. The mildest day should occur on Tuesday as high pressure slides off the east allowing southerly flow to boost readings into the 40s for most spots. A cold front will then cross the area Tuesday night into early Wednesday with a renewed threat of light rain/snow shower activity. Behind this front conditions trend mainly dry from Wednesday night onward into late week under a seasonably cold late Autumn airmass. An early look at the Thanksgiving holiday suggests partly cloudy skies and dry weather, though on the chilly side with temperatures mainly in the lower and mid 30s. No large scale travel concerns are expected. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... Through 18Z Saturday...Mix of MVFR and VFR currently will trend to VFR/SKC at all sites by 00Z and remain VFR through the remainder of the period with mid/high clouds increasing from west to east after 00Z. Northwest winds gusting 20-25kts through the afternoon will go light/calm after sunset before turning southerly and increasing to 5-15kts after 12Z Saturday. Outlook... Saturday Night: Mainly MVFR, with areas IFR possible. Definite RA, Likely SN. Sunday: MVFR/IFR conditions possible. Windy with gusts to 35 kt. Likely RA, Chance SHRA, Chance SHSN. Sunday Night: Mainly VFR, with local MVFR possible. Chance SHSN. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: Mainly VFR, with local MVFR possible. Slight chance SHRA. Tuesday Night: VFR. Chance SHRA, Chance SHSN. Wednesday: Mainly VFR, with local MVFR possible. Slight chance SHRA, Slight chance SHSN. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...Lahiff SHORT TERM...JMG LONG TERM...JMG AVIATION...Lahiff

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